Motor vehicles, particularly large vehicles such as trucks, recreational vehicles, buses, etc. have certain areas known as "blind spots." These blind spots are areas where it is difficult or impossible for an operator sitting in the driver seat of the vehicle to observe. Blind spots may exist on the sides or at the rear of a large vehicle. Other blind spots are often in areas at the front or rear of the vehicle as well as underneath the vehicle. It is important that a driver be able to view the blind spots to prevent accidents when the vehicle is in motion. In addition, it is important for the driver to view such blind spots to avoid attack or vandalism while the vehicle is parked.
Prior art efforts related to allowing drivers to view blind spots have included the use of mirrors at various locations on the vehicle. Mirrors enable the driver to better see the areas in the front and to the sides of the vehicle. Such mirror systems typically involve parabolic lenses that provide the driver with a distorted view.
Unfortunately, it is impossible to use mirrors to enable a driver to see certain areas around the vehicle. For example, a mirror system cannot be used to view the area directly behind or underneath a semi-trailer. In viewing the rear area of a vehicle, some have suggested the use of closed-circuit TV cameras. The use of such closed-circuit TV cameras has posed problems however. These problems have included the need for special dedicated wiring in the vehicle to operate the camera and to transmit signals. Such wiring is expensive to retrofit in a vehicle and also requires special connections when the camera is on a trailer or similar unit that is separable from a tractor or other unit that holds the driver. Such closed-circuit TV camera systems also present problems with regard to providing a limited field of view that may not represent what a driver is accustomed to seeing in a rear-view mirror. This is because the camera does not provide a reversed image. In addition, the proper functioning of cameras requires the maintenance of suitable environmental conditions within the camera housing that is difficult to maintain in cold or wet conditions.
A further drawback associated with closed-circuit TV cameras is that they are exposed to a variety of lighting conditions. For example, sun-glare can have the effect of "blinding" the camera, particularly during the hours near sunrise and sunset. After dark, the headlights of other vehicles present a sharp contrast to the surrounding darkness and can often result in a blinding effect. Cameras have not been placed near the underside of motor vehicles because of shadows and generally insufficient light for viewing in these areas. All of these factors have traditionally made closed-circuit television systems unsatisfactory in motor vehicles.
There is also a growing trend toward making the cabins of motor vehicles quieter. This is necessary, both to protect the hearing of the operator as well as to avoid fatigue that may result from noise and vibration. Long distance driving in large vehicles is often very fatiguing and significant sound and vibration increase the fatiguing effect. The need for temperature control within the cab of the motor vehicle has resulted in such vehicles typically being operated with the windows up. This further helps to reduce the sound level within the cab.
An unfortunate drawback that comes with the advantages of having a quiet and environmentally controlled space for the driver, is that the driver is not aware of many sounds surrounding the vehicle. This presents problems in a number of circumstances. Such circumstances include when the vehicle is near a railroad crossing and the noise or horn of an oncoming train cannot be readily heard in the cab of the vehicle. In addition, pedestrians who are in the vicinity of the vehicle may not be visible to the driver, but may be struck when the vehicle begins to move. The noise being made by the pedestrians can help the driver discern their location.
Vandals who might attack a vehicle when it is sitting in a rest area or at a stop light cannot be heard approaching from the sealed cab. In addition, it is also often helpful to have an individual on the ground to guide the driver when backing the vehicle into a loading dock or moving it onto a rail car. However, such an individual may not be readily heard from the driver's position in many circumstances.
A further problem with existing closed-circuit cameras is that they require enclosures that are of significant size. It is readily apparent to anyone observing the vehicle that the enclosure houses a TV camera. As a result, vandals are often prone to stealing the cameras and enclosures when the vehicle is parked or not attended.
Thus, there exists a need for a system and devices that enable an operator of a motor vehicle to view the areas surrounding the motor vehicle, particularly the blind spots. Further there is a need for a system and devices that enable the operator of a motor vehicle to hear the sounds adjacent to the motor vehicle to avoid accidents and vandalism. There is further a need for systems and components that can withstand the harsh environmental conditions commonly encountered on a motor vehicle and which can be packaged in a manner that prevents their detection by vandals and others.